Page - 257 - in Emerging Technologies for Electric and Hybrid Vehicles
Image of the Page - 257 -
Text of the Page - 257 -
Energies 2017,10, 616
It is clear that thephasevoltageofmotorchanges followsasinusoidalwaveform;amplitudesof
phasevoltage instar, triangleandindependentmodes increased insequence. Fromthe local curveof
phaseAâsvoltage, therewereďŹvephasevoltagevalues,â2Vdc/3,âVdc/3,0,Vdc/3,and2Vdc/3,when
themotorwas instarmode. Therewereonly threephasevoltagevalues,âVdc, 0, andVdc,whenthe
motorwas in trianglemode; ifwe ignore thevoltagedifferencebetweenthe twosidesâpowersources,
therewereninephasevoltagevalues,â4Vdc/3,âVdc,â2Vdc/3,âVdc/3, 0,Vdc/3, 2Vdc/3,Vdc, and
4Vdc/3whenthemotorwas in independentmode,whichmadethecurrentcontrolmoresmooth. The
phasecurrentof themotor changedaccording to thesinusoidal rule; becauseof thezero-sequence
currenteffect, theamplitudeof thephasecurrent in trianglemodewasslightlygreater thanthose in
starandindependentmodeswith thesameamplitudeofstatorâs current. FromFigure8d,wecansee
thatafter switchingfromstarmodeto trianglemode, thewaveformofphasecurrentchangedandwas
nolongerastandardsinusoidalwaveformdueto thezero-sequencecurrent,which ledtooccupation
of the inverterâsextracapacityandincreasingswitchingfrequencyofdevices.At thesametime, the
phasecurrentwasrestricted in thehysteresisbandandthecurrent followedaccordingly.
Total switching frequencyof inverterdevices (sumofall IGBTdevicesâ switching frequencies)
of both theproposedand the contrastingmodel is shown inFigure9a. Invertersâ loss is shown in
Figure9b.
(a) Total switching frequency of inverter devices
(b) Invertersâ loss curves
Figure9.Curvesof total switchingfrequencyof inverterdevicesandinverter loss.
FromFigure9a,wesee that theswitching frequenciesof inverterdevices in trianglemodeare
higher thanthose instarmodebecause thephasevoltagevalues in trianglemodeare lowerandtheir
amplitudesweregreater, leadingtoahigherchangingrateofphasecurrentandmorefrequentlyhitting
thehysteresisboundary; the total switching frequencyof inverterdevices in independentmode is
alsohighdueto the twoinvertersworkingtogether in independentmode.However, thereweremore
phasevoltagevalues in independentmodeandthecontrolof thephasecurrentcouldbemoresmooth
257
Emerging Technologies for Electric and Hybrid Vehicles
- Title
- Emerging Technologies for Electric and Hybrid Vehicles
- Editor
- MDPI
- Location
- Basel
- Date
- 2017
- Language
- English
- License
- CC BY-NC-ND 4.0
- ISBN
- 978-3-03897-191-7
- Size
- 17.0 x 24.4 cm
- Pages
- 376
- Keywords
- electric vehicle, plug-in hybrid electric vehicle (PHEV), energy sources, energy management strategy, energy-storage system, charging technologies, control algorithms, battery, operating scenario, wireless power transfer (WPT)
- Category
- Technik